1. Field of the Invention
The present invention relates to a small-sized pump device that is used as means for sending air into a cuff band member for use on a blood pressure meter or into various kinds of air supplies and applying pressure to its interior, and a blood pressure meter using this small-sized pump device.
2. Description of the Related Art
A general type of blood pressure meter has an appearance such as that illustrated in FIGS. 38(A) and 38(B) and has a construction illustrated in FIG. 39.
When having its main body cover 79 demounted, the blood pressure meter has equipped therein an electromagnetic valve 87, a display panel 81, a control circuit 93, a small-sized. pump device 91, a pressure sensor 89, and a slow leak valve 85. The cuff band member 83 and a group of the small-sized pump device 91, slow leak valve 85, electromagnetic valve 87, and pressure sensor 89 are connected to each other by means of a hollow tube 95.
And, when turning on a measuring switch after a power source is supplied to the blood pressure meter, the electromagnetic valve is closed, and the small-sized pump device performs its pumping operation to thereby speedily send air into the cuff band member and thereby pressurize the same. And, when the pressurization of the cuff band member up to a set value has been sensed by the pressure sensor, the small-sized pump device is stopped. And the pressure within the cuff band member is reduced by gradually discharging the air therewithin at a fixed speed through the slow leak valve. And while this pressure is being reduced, measurement is performed of a change in pressure and measurement is performed of the blood pressure value and the pulsation. After completion of such measurements, the electromagnetic valve is released in order to speedily discharge the air remaining within the cuff band member. And display is made of the measurement results on the display panel.
The above-described operation will now be explained with reference to a flow chart of FIG. 40 illustrating a pneumatic system as well as with reference to an electric block diagram of FIG. 39. First, the cuff band member 83 that is connected to the blood pressure meter is wound around the arm to thereby make preparations for measurement. Next, when having turned on the power source button of the blood pressure meter, the conditions to be set in the pressurization, etc., are displayed on the display panel 81. Here, in a case where set conditions to be set in the pressurization should be changed, this change can be made by operating pressurization set buttons. In a case where performing no changes in the set conditions, a push is made on a measurement-starting button.
When the measurement-starting button is pushed, an electric power is supplied to the electromagnetic valve 87, whereby the electromagnetic valve 87 is closed.
Almost simultaneously with this, the power is also supplied to the small-sized pump 91, whereby air is sent into the cuff band member 83 by the small-sized pump 91.
Regarding the pressured value within the cuff band member 83, into which air is sent, the analog signal obtained from the pressure sensor 89 is converted to a digital value by an A/D converter circuit, which is arbitrarily detected by a microcomputer (the control circuit 93). The power is supplied to the small-sized pump 91 until the pressure value within the cuff band member reaches from 0 mm Hg to the pressure value of the set conditions for the pressurization (e.g., a set value ranging from 160 to 280 mm Hg).
The control circuit compares the digital value with the set value and, when the digital signal is smaller than the set value, continues to drive the pump. When the pressure within the cuff band member 83 reaches the set value, the control circuit stops the small-sized pump device 91. On the other hand, the slow leak valve 85 gradually discharges the air within the cuff band member 83 with units of a fixed amount (several mm Hg/sec) and thereby goes on reducing the pressure therewithin.
During this time period, the fluctuation in the pressure in the cuff band member is measured as pulse waves by the pressure sensor 89 and is sampled at prescribed intervals by the microcomputer 93.
By the pulse waves being detected, the maximum blood pressure, the minimum blood pressure, and the pulsation are respectively determined. Generally saying, at the point in time when the pressure reduction has been made up to approximately 50 mm Hg, the measurement of the maximum blood pressure value and the minimum blood pressure value are ended. A time period required in doing so, will be about 30 seconds.
After that determination, a signal indicating the end of the measurement is generated, whereby the supply of the power to the electromagnetic valve 87 is stopped and the cuff band member 83 is released. As a result of this, the air having remained within the cuff band member 83 is speedily discharged, whereby the pressure value is made to be 0 mm Hg.
Along with this, the maximum blood pressure value, the minimum blood pressure value, and the pulsation times, which are the measurement results, are displayed on the panel of the display portion 81.
And, as the small-sized pump device used in the above-described blood pressure meter, there is the one that is shown in, for example, Japanese Patent No. 2551757. Illustration is made of this pump device in FIG. 41. A reference numeral 101 denotes a small-sized DC motor. A reference numeral 103 denotes an output shaft of a small-sized DC motor 101; a reference numeral 105 denotes a case that has been mounted on an output shaft surface of the small-sized DC motor 101. A reference numeral 107 denotes a collar that has been mounted on the output shaft 103. On the collar 107 is mounted a drive shaft 109 that is inclined at a prescribed angle with respect to the output shaft 103 and a forward end of that exists on a center axis of the output shaft 103. A reference numeral 111 denotes a drive member that is formed into the shape of a circular plate. Also, a reference numeral 113 denotes a diaphragm member and a reference numeral 115 denotes a diaphragm portion that is shaped like a hanging bell extended downward from the diaphragm member 113 and formed integrally therewith. And a reference numeral 117 denotes a drive portion located at the center of the diaphragm portion. A reference numeral 119 denotes a valve element portion that is shaped like a circular-cylindrical configuration extended upward from the central portion of the diaphragm member 113 and formed integrally therewith. The drive portion 117 is forcedly inserted into a hole of the drive member 111 and is retained thereby. A reference numeral 121 denotes a lid member. The lid member 121 is fixed to the case 105 with the diaphragm member 113 being clamped between the lid member 121 and the case 105. Pump chambers 123a, 123b are formed by the space formed between the lid member 121 and the diaphragm portion 115. A reference numeral 125 denotes a valve chamber portion formed in a central portion of the lid member 121 in such a way as to be directed upward, and 127 denotes an exhaust port. The valve element portion 119 is in contact with the inner-peripheral surface of the valve chamber portion 125 and is arranged to close the passage. A reference numeral 129 denotes a spherical valve element member, which has formed therearound a plurality of suction openings 131.
In the small-sized pump device that has been constructed as mentioned above, upon rotation of the output shaft 103 due to the supply of an electricity to the small-sized DC motor 101, the drive shaft 109 rotates together with the collar 107. As a result of this, the drive member 111 makes a countersunk turn motion, whereby the drive portion 117 of the diaphragm member 113 is vibrated in the vertical direction. The volume of the pump chamber 123 is thereby periodically changed. When the volume increases due to the downward movement of the drive portion 117, the pump chamber 123 is pressure-reduced, whereby the valve element portion 119 closes the valve chamber portion 125 by being brought into close contact with the valve chamber portion 125. Conversely, the valve element 129 is opened, whereby air is made to flow from the suction opening 131 into the pump chamber 123a or 123b. Next, when the volume decreases due to the upward movement of the drive portion 117, the pump chamber 123a or 123b is pressure-increased, whereby the valve element 129 is closed due to its close contact with the lid member 121. The valve element portion 119 is conversely brought to a state of being flexed inward, with the result that the valve element portion 119 is opened. The air within the pump chamber 123a or 123b is discharged from an exhaust port 127.
However, in the blood pressure meter using the small-sized pump device performing the above-described pumping operation, as a mechanism for converting the rotational movement of the motor to a linear movement, in the first conventional example, there are used the inclined shaft and the drive member for making a countersunk turn movement. For this reason, in the compression/expansion strokes of the air chamber, the air chamber is distorted, raising the problem that in the suction/expansion strokes of the air chamber the efficiency is poor.
This drawback will now be explained with reference to FIG. 42. It is to be noted that in FIG. 42 illustration is made of a case where the air chamber is one in number.
FIG. 42(a) illustrates the suction stroke, in which the inclined shaft is inclined. Therefore, the coupled portion between the air chamber and the drive member is pulled in the rightward/downward direction. And it is seen that the air chamber is also expanded in a state of being expanded.
Also, at an intermediate position of the suction/exhaust strokes of FIG. 42(b), the inclined shaft is vertical with respect to the air chamber. At this stage, the force can be made to act upon the air chamber from right below the same.
However, in the exhaust stroke of FIG. 42(c), the inclined shaft is again inclined. Therefore, the joined portion is pushed up in the rightward/upward direction. It is therefore seen that the air chamber is also compressed in a state of being distorted.
Also, in the blood pressure meter using the small-sized pump device that has been shown as the first conventional example, at the time of starting, the load that is applied to the output shaft of the motor is great. This raised the problem that the current value at the time of starting became great.
Also, as one of the characteristics the pump device of the blood pressure meter is demanded to have, there is a re-pressurization characteristic.
The re-pressurization characteristic is the one that is obtained by evaluating whether when having again applied a minimum voltage value in the range of use voltage from a state where pressurization has been made to 200 (20 mm Hg the pump device can be started and thereafter pressurization can be made up to 300 mm Hg.
Illustration about the load applied to the motor is shown in FIG. 45. It is to be noted that in FIG. 45 illustration of a force applied to one air chamber is made.
To the output shaft of the motor are mounted the collar, the drive shaft, and the drive member. To this drive member is coupled the diaphragm portion that is shaped like a hanging bell.
At this time, it is assumed that F represents the force that is generated when compressing and expanding the diaphragm. Under this assumption, it is assumed that the F acts upon the drive member; and R1 represents the distance from the output shaft to the point of action. Then, a moment of Fxc3x97R1 acts on the output shaft of the motor as a force making the output shaft of the motor eccentric. As a result, the load upon the motor becomes high and in consequence the current value at the time of starting becomes great.
In a case where re-pressurization is made, since the pump device is in a state of pressure as high as 200 (20 mm Hg, it is clear that the value of the F becomes greater than that when no load is applied. Accordingly, the load upon the motor also becomes higher.
A second example of the conventional small-sized pump device is illustrated in FIG. 43. This small-sized pump device 65 is constructed generally of a drive source 66, a drive transmission portion 67, a pump portion 68, and a suction/exhaust portion 69. For the drive source 66 there is generally used a small-sized DC motor 70.
The drive transmission portion 67 performs its pumping operation that is done by compressing and expanding an air chamber 72 of the pump portion 68, by converting the rotational movement of an output shaft 71 of a DC motor 70 constituting the drive source 66 into, for example, vertical reciprocating movements.
Following this pumping operation, the air within an air chamber 72 is extruded into an exhaust opening 73 and an exhaust port 74 and is then supplied to the cuff band member of the blood pressure meter. In the conventional example illustrated in FIG. 43, in order to convert the rotational movement of the DC motor 70 into reciprocating movements, the following construction is adopted.
A circular-cylindrical surface cam 75 is mounted on the output shaft 71 of the DC motor 70. On an outer-peripheral surface of this circular-cylindrical surface cam 75 is formed a concaved groove that is smooth and that is inclined with respect to the direction of the output shaft 71 with one full round being made per one full circumference (one cycle of the vertical movement is complete with one full circumference being ended with one full round thereover). The drive member 76 that has been swingably retained at one end by the case is supported at the other end by the concaved groove of the circular-cylindrical surface cam 75. It is thereby arranged that the drive member 76 make its vertical reciprocating movements along the concaved groove due to the rotation of the circular-cylindrical surface cam 75.
Due to the vertical reciprocating movements of the drive member 76, the air chamber 72 is compressed and expanded. In the figure, air is sucked in through a suction opening 77 through the expansion of the air chamber 72. Also, through the compression of the air chamber 72, the air inside is discharged from within the air chamber 72 through an exhaust opening 73. Further, the air inside is supplied to the cuff band member through the exhaust port 74.
And in this arrangement in the suction stroke from the suction opening 77 into the air chamber 72 as well as in the exhaust stroke from the air chamber 72 into the exhaust opening 73, a suction valve 78 and an exhaust valve 79 are used as check valves for preventing back flow of the air. Each of these valves is made of elastic material such as soft rubber and, as illustrated in FIG. 44, its valve portion is disposed in such a way as to cover the suction opening 77a and the exhaust opening 73 both provided in a housing. At an ordinary time, there prevails a state where landing portions of the outer-peripheral edges of the suction valve 78 and the exhaust valve 79 are in contact with a seal surface of the housing.
In the suction stroke, the air chamber 72 is pulled by the circular-cylindrical surface cam 75 and the drive member 76 in the downward direction and thereby sucks the air in. At this time, the air lifts up the landing portion of the outer-peripheral edge of the suction valve 78 via the suction opening 77a and is supplied to the interior of the air chamber 72 via the suction opening 77b as illustrated in FIG. 44. At this time, regarding the exhaust valve 79, the internal pressure of the cuff band member of the blood pressure meter act thereupon. Therefore, the landing portion of the outer-peripheral edge of the exhaust valve 79 is closely contacted with the seal surface of the housing with no clearance existing in between. The back flow of the air is thereby prevented.
Also, in the exhaust stroke, the air chamber 72 is pushed up by the circular-cylindrical surface cam 75 and the drive member 76 in the upward direction and thereby the air within the air chamber 72 is compressed. And, the thus-compressed air lifts up the landing portion of the outer-peripheral edge of the exhaust valve 79 via the exhaust opening 73 and is discharged to outside the air chamber. The air is thereby supplied to the interior of the cuff band member of the blood pressure meter. In this exhaust stroke, regarding the suction valve 78, the internal pressure of the air chamber 72 acts thereupon. Therefore, the landing portion of the outer-peripheral edge of the suction valve 78 is closely contacted with the seal surface of the housing with no clearance existing in between. The back flow of the air is thereby prevented.
Further, in the blood pressure meter using the small-sized pump device performing the above-described pumping operation, the compressing/expansion movement of the diaphragm is performed along the circular-arc orbit the center of whose circle is located at the retaining portion of the drive member. Therefore, at the time of compression, the air chamber cannot completely be compressed. This raised the problem that the maximum pressurizing force, which is one of the important characteristics of the for-use-in-blood-pressure-meter pump device, was small.
Also, in the small-sized pump device that has been above described as a conventional example, by the landing portions of the outer-peripheral edges of the suction valve 78 and the exhaust valve 79 being uplifted by pneumatic pressure, suction and exhaust of air are performed. However, the landability of the outer-peripheral edge of each valve with respect to the seal surface is bad. This raised the problem that when the pressure was low the leak (the back flow) of the air occurred.
Also, in the blood pressure meter using the small-sized pump device performed the above-described pumping operation, the drive member is positioned by being inserted into a drive member mounting groove and set therein. Therefore, following the vertical movement of the drive member, sounds generate between the fixed end thereof and the drive member mounting groove. This raised the problem that these sounds became noises.
Also, since the free end of the drive member is substantially circular-columnar, it is necessary to make the width of the concaved groove of the circular-cylindrical surface cam greater than the diameter of the free end. As a result of this, a clearance is necessarily produced between the two. The sounds that generate between the free end and the concaved groove of the circular-cylindrical surface cam during the rotation are therefore considered as being problematic.
And, in a case where having formed the circular-cylindrical surface cam by integral formation, the groove becomes substantially shaped like a trapezoidal wave. Therefore, in the vicinity of an apex of the groove, the free end is rapidly changed in terms of its direction. Therefore, the sounds that generate between the free end and the groove were also problematic.
Further, since the suction opening is provided in correspondence with the position of the suction valve, it was problematic that the sounds of opening or closing of the suction valve leaked directly into outside the pump device to become noises. For this reason, there was the problem that the noises, which are one of the important characteristics of the for-use-in-blood-pressure-meter pump device, were high in magnitude.
Under these circumstances, the present invention has an object to provide a small-sized pump device which, especially in the blood pressure meter, in order to enable compression and expansion carried out in the compression and expansion stroke in the air chamber by converting the rotational movement of the motor to a linear movement, to be made without causing rightward or leftward distortion of the air chamber, can perform a highly efficient pumping operation.
Also, it is another object of the present invention to provide a small-sized pump device which can reduce the load applied onto the motor to thereby decrease the current value at the time of starting and can also easily procure the repeated pressurization characteristic, and a blood pressure meter using the same.
Further, it is still another object of the present invention to provide a small-sized pump device that has decreased the noises generated, and a blood pressure meter using the same.
It is a further object of the present invention to provide a small-sized pump device wherein the compression ratio has been increased; and the maximum pressurizing characteristic has been enhanced, and a blood pressure meter using the same.
The present invention has an object to solve the above-described problems, and provides a small-sized pump device, the efficiency of that has been increased by preventing air from being leaked (making a back flow) at the time of low pressure when the pump operation is started.
To attain the above object, the small-sized pump of the present invention is the one that includes a drive source, a drive transmission portion that is engaged with the drive source, a pump portion that includes an air chamber engaged with the drive transmission portion, and a suction/exhaust portion that includes a suction valve and an exhaust valve, each of that is communicated with the air chamber of the pump portion, wherein the drive transmission portion has a cylindrical member, rotatably-supported on a drive output shaft of the drive source, a cam portion formed on a surface of the rotary cylindrical member so as to show a spiral configuration while having a prescribed angle with respect to a rotation axis of the rotary cylindrical member, and a drive member a part of that is engaged with the cam portion; and the air chamber is constructed so that an internal volume thereof may be compressed and expanded according to the displacement movement of said drive member, that is contacted to the air chamber and responding to the rotation movement of the cam portion.
To attain the above-described object, the present invention provides a small-sized pump device that includes a drive source, a drive transmission portion, a pump portion, and a suction/exhaust portion, and in that the drive transmission portion has a circular-cylindrical surface cam rotatably-supported by the motor and a drive member moved up and down by the circular-cylindrical surface cam, whereby the air chamber is pressed by the drive member. By constructing the drive transmission portion by the cam mechanism in the above-described way, it becomes possible to transmit the energy from the drive source with a high efficiency compared to the conventional arrangement.
To attain the above-described object, the present invention provides a small-sized pump device that includes a drive source, a circular-cylindrical surface cam rotatably supported by the output shaft, a drive transmission portion having a drive member moved up and down by the circular-cylindrical surface cam and constructed so as to press the air chamber by the drive member, a pump portion, and a suction/exhaust portion. The suction/exhaust portion is constructed by an exhaust valve holder, and, at the coupled portion formed between the suction/exhaust portion and the air chamber, a pressure-adjusting portion for making a pressure adjustment is provided. Especially, the configuration of the pressure-adjusting portion is made to be the one that depends on the enhancement of the pressurization characteristic. This enables the provision of a small-sized pump device having excellent pressurization characteristics.
Specifically, the pressure-adjusting portion is characterized by having a convexed portion formed at the coupling portion formed between itself and the air chamber, the bottom surface of the convexed portion having an inclined structure. Further, it is also a characterizing feature that the bottom surface of the convexed portion is substantially parallel with a line connecting the fixed end of the drive member and the apex portion of the concaved groove. Or, it is also a characterizing feature that the sectional configuration of the convexed portion of the exhaust valve holder is substantially the same as that of the air chamber. As a result of this, it becomes possible to provide a pump device having excellent pressurization characteristics.
To attain the above-described object, the present invention provides a small-sized pump device that includes a drive source, a drive transmission portion, a pump portion, and a suction/exhaust portion, in which it is a characterizing feature that the suction/exhaust portion includes a suction-valve/exhaust-valve integrated sheet wherein a sheet-like suction valve holder and a sheet-like exhaust valve holder are integrated together, and a suction valve holder and an exhaust valve holder each of that holds this sheet respectively; and in the periphery area of the suction opening and exhaust opening formed in these holders suction/exhaust pressure-adjusting portion is provided.
The suction/exhaust pressure-adjusting portion is characterized by being provided with an inclined and convexed step-like portion on the neighboring portion to the portion on which either one of the suction opening and exhaust opening of the suction valve holder and exhaust valve holder, or the both are formed.
By equipping such inclined and convexed step like portion, even at the time of low pressure, a higher tension is applied to the contacting portion of the outer-peripheral edge of each of the suction and exhaust valves. Therefore, the contacting characteristic of the outer-peripheral edge of the valve with respect to the seal surface is improved. This can prevent the leak (back flow) of the air during a low-pressure time when the pumping operation is started.
To attain the above-described object, the present invention provides a small-sized pump device that includes a drive source, a circular-cylindrical surface cam that is rotatably-supported by the output shaft, a drive transmission portion wherein the air chamber is pressed by a drive member moved up and down by the circular-cylindrical surface cam, a pump portion, and a suction/exhaust portion, and in that the drive member is formed integrally with a frame member portion through a fixed end portion thereof. As a result of this, it has become possible to provide a small-sized pump device having excellent anti noise characteristics.
Also, there is the characterizing feature as well that the free end of the drive member is substantially spherical.
Further, there is also the characterizing feature that the concaved groove of the circular-cylindrical surface cam is formed as a sine wave.
And it is possible to provide a small-sized pump device which has had its noise characteristic improved also by equipping the pump device with a case lid member constituting the suction/exhaust portion.